Correct option is (2) Hydrometer
The fundamental component of a hydrometer is a weighted, sealed, long-necked glass bulb submerged in the liquid being measured.
The density of the liquid is indicated by the flotation depth, and the neck of the hydrometer can be calibrated to read the actual gravity value.
Archimedes' principle is the foundation of a hydrometer used to measure the density of liquids.
